AN1139 STMicroelectronics, AN1139 Datasheet - Page 36

• Manufacturer Part Number: AN1139
• Description: L6254 - L6268 - L6269 12V DISK DRIVE POWER COMBO IC
• Manufacturer: STMicroelectronics

AN1139 APPLICATION NOTE
6.0 APPLICATION & TOOLS
6.1
Altought the Device offers the complete BEMF processing and Speed Control Loop inside, the possibility may
exists where certain applications might require complete microprocessor control of those functions. The flexible
architecture of this device give the P the option to externally provide those features. The figure #18 depicts the
Stand Alone configuration where the Bemf processing and Speed Control Loop are demanded to the Power
Combo. In this case the P has to provide the SYSCLK frequency and POR signal has to be monitored for under
voltage detection. FCOM and the status register may also be monitored for fault condition. The registers have
to be programmed once according to the desired bits configuration.
Figure 18. Stand Alone Application Configuration
The Figure #19, shows the External Bemf processing configuration. In this case the FCOM pin has to be con-
tinuously monitored and the commutation signal has to be provided to INDEX pin (#11). An explanation of this
configuration setup can be found in chapter 4 (Spindle Circuits), section 4.11 (External BEMF Processing op-
tion).
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APPLICATION CONFIGURATIONS
Microprocessor
or DSP
SYSCLK
SDATA
SDEN
FCOM
SCLK
POR
B E M F P R O C E S S I N G
S P E E D C O N T R O L
P O W E R C O M B O
L O O P
V O I C E C O I L
S P I N D L E
M O T O R
M O T O R